Association of body mass index and clinical response in patients receiving ofatumumab for treatment of multiple sclerosis

Background The impact of body weight on disability progression rates among patients receiving ofatumumab was not evaluated yet. Methods Among patients from a multicentre prospective cohort, baseline demographics were compared among body mass index (BMI) quartiles as well as proportions of clinical relapses, MRI lesions and disability worsening during follow-up. Results 536 patients from four centres were included. Baseline demographics were evenly distributed among patients. Proportions of relapses and new/enlarging MRI lesions were comparable among BMI strata. Confirmed disability worsening was significantly more abundant among patients from the 4th BMI quartile (BMI ≥29.2 kg/m 2 ; adjusted HR: 3.33 (95% CI: 1.72 to 6.42; p<0.001). Relapse-associated worsening was not substantially different among relapsing patients from different BMI strata (HR: 1.19 (95% CI: 0.40 to 3.52; p=0.750)). Yet, progression independent from relapse activity was more likely in patients from 4th BMI quartile (HR: 2.00 (95% CI: 1.47 to 2.70; p<0.001)). Body weight (4th body weight quartile: ≥84.5 kg) was not associated with disability worsening (adjusted HR: 1.91 (95% CI: 0.97 to 3.76; p=0.060). Ofatumumab serum levels were lower in patients with higher BMI as well. Conclusions Inflammatory disease outcomes did not differ but disability progression was more frequent in the highest BMI quartile (BMI >29.2 kg/m 2 ). This was associated with lower ofatumumab serum levels. Since body weight itself was not predictive, we assume that body fat composition is critical for ofatumumab effectiveness.